Commonly found prior art collimator arrays, as typically shown in FIG. 1, generally use an input fiber array 10 and a lens array 12 constructed from separate elements, and mechanically aligned opposite each other, so that the light from each fiber impinges centrally on its associated lens. The fiber array itself commonly comprises a silicon V-groove mechanical structure 14 with a single mode, bare fiber 16, typically with a diameter of 125 μm, aligned and clamped by means of a cover plate inside each V-groove. Both V-groove structure 14 and lens array 12 are mounted on a base plate 18. The accuracy of spacing between the fibers is generally no better than ±0.5 μm, and due to the nature of the assembly process and the production spread of fiber diameter, often not even that good. Additionally, the silicon array itself can have mechanical deformations that too affect the fiber position accuracy.
The lens array is generally made of either silicon or glass, and it too has limited positional accuracy. Furthermore, the lenses themselves may have deviations in the radius of curvature arising from the manufacturing process.
An additional and often the major source of inaccuracy arises from the process of aligning and assembling the two elements, the input fiber array and the lens array, which is a challenging task requiring much effort and time. Some alignment errors, such as lateral misalignment of the two parts, can be compensated for elsewhere in the system, since the collimated array of light beams are still coplanar. However, an angular twisting misalignment between the two elements results in a three dimensional fanning out of the array of collimated light beams, and this cannot be compensated for, such that the total device performance is degraded.
There therefore exists a need for a collimator array which overcomes some of the disadvantages of such prior art arrays.